A theoretical study of the DMS·OH scavenging reaction by OH. Its relevance in DMSO formation

In this work, an exhaustive electronic structure characterization of the DMS·OH + OH reaction has been performed. The corresponding dynamical analysis by means of variational transition-state theory has also been carried out with the aim of finding out the most feasible products of this scavenging reaction. Our results have shown that two final pairs of products DMSO + H2O and CH3S(OH)CH2 + H2O can be formed. The first process is clearly more exergonic. From a kinetic point of view and taking into account the shortest pathways, we have shown that the CH3S(OH)CH2 + H2O final products are favored in comparison with DMSO + H2O. However, the CH3S(OH)CH2 species has never been experimentally detected. In this paper, we have found longer reaction pathways, which involve movements of the H2O fragment within the molecular complexes and intramolecular hydrogen transfers, that clearly lead to DMSO + H2O. Then, we can conclude that the DMS·OH + OH reaction contributes to the DMSO yield within the global DMS + OH reaction.